The present invention relates to electromagnetic devices for automatically actuating piano keys.
Various types of apparatus are known in the art for automatically actuating piano keys. One such apparatus, for example, is the old roll-type player piano. This type of piano, however, has many disadvantages, among which are the large space required for storage of paper rolls, the high cost of the rolls, the inconvenience of loading and unloading the rolls in the piano, the high cost of repairing the piano and the complexity of the piano, which includes bellows or vacuum pumps, and the inability to provide variations in the intensity and duration of notes played.
More recently, to overcome most of the disadvantages associated with using paper rolls to control operation of a player piano, magnetic recording tapes have been used to record and then play back musical notes on a piano. Some advantages to the use of tapes are that the piano key actuating mechanisms may be made to be less complex and expensive to build and maintain. Also, there is no problem of tearing the recording media, the tapes are capable of storing a large quantity of recorded data in a relatively small space, and they are much less costly and easier to produce than perforated rolls. Furthermore, if a casette type tape player is used, it is never necessary to touch the actual tape, which is simply plugged in or out.
Inasmuch as magnetic tapes are capable of storing high density recorded data, it is possible with tapes to readily and conveniently store data representative both of the intensity of notes to be played, or of the force used to actuate piano keys, and of the duration for which notes are to be held. To take advantage of and utilize the relatively great data density of a tape, recent developments also contemplate use of electromagnetic actuation for piano keys, inasmuch as electromagnets are readily responsive to suitably processed signals from a magnetic tape and generally provide a significant degree of control over the intensity and duration of notes played at the least expense. However, even such simple devices as electromagnets have not heretofore found favor in the piano industry as a means for actuating piano keys, because substantial modifications in a piano structure have had to be made to incorporate electromagnetic actuating systems therein, and complex and expensive equipment has been necessary to cause the systems to apply forces to the keys which are similar to those which would otherwise be applied by hand. In addition, conventional electromagnetic piano key actuating systems usually produce clicking sounds when a key is struck or played, and have not been well suited to rapid key reaction times or stacatto playing. For representative examples of electromagnetically actuated player pianos, reference is made to U.S. Pat. Nos. 3,141,368, 3,149,528, 3,160,052, 3,195,389, 3,647,929, 3,789,719, 3,895,554, 3,905,267 and 4,132,141.